sum = [0, 1, 1]
long = int(input("请输入你想要得到多少位的数列："))
if long > 0:
    for i in range(long-1):
        sum.append(sum[-3] + sum[-2]+sum[-1])
    print("数列：", sum[1:])
else:
    print("请输入正整数！")